Lowest Average Speed of Gases at 25C: H2S

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At 25°C, H2S has the highest molar mass among the gases listed, which suggests it should have the lowest average speed according to the formula sqrt(3RT/M). The discussion confirms that the kinetic energy of each gas molecule is equal at the same temperature, reinforcing that molar mass inversely affects speed. The gases compared are NH3 (17.03 g/mol), O2 (32 g/mol), H2S (34.08 g/mol), and CH4 (16.04 g/mol). Therefore, H2S is indeed expected to have the lowest average speed among these gases. Understanding the relationship between molar mass and molecular speed is crucial in gas behavior analysis.
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Which of the following gases has the lowest average speed at 25C?
a.NH3
b.O2
c.H2S
d.CH4
Is it H2S? Given the formula sqrt(3RT/M), is it not true that the gas with the greatest molar mass will have the lowest speed?
NH3 = 17.03 g/mol
O2 = 32 g/mol
H2S = 34.08 g/mol
CH4 = 16.04 g/mol
Thanks.
 
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Yes, the KE of each molecule (at the same Temperature) is the same.
KE = ½ m v^2 = 3/2 k_B T
If you haven't seen it yet, k_B = k_Boltzmann = R/N_Avagadro
 

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